Packaged semiconductor dies, including memory chips, microprocessor chips, and imaging chips, typically include one or more semiconductor dies mounted on a substrate and at least partially encased in a protective covering. The dies include functional features, such as memory cells, processor circuits, and imaging devices, as well as bond pads electrically connected to the functional features. The bond pads can, in turn, be electrically connected to terminals outside the protective covering to allow the die to be connected to higher level circuitry. Additionally, in devices having multiple dies (e.g., vertically stacked dies), interconnects or pillars can electrically connect adjacent dies via corresponding bond pads.
To provide a reliable and robust electrical connection, conductive materials that are connected to the bond pads need to be securely and uniformly bonded thereto. However, the fabrication of packaged semiconductors typically includes one or more processes that expose the bond pads and/or the conductive materials to corrosive chemicals that can corrode, degrade, or otherwise interfere with the bond between the bond pad pads and the conductive materials. A variety of techniques are used to minimize the adverse effects of the corrosive chemicals, but existing fabrication processes present opportunities for corrosion at the bond pads that can lead to degradation or failure of the electrical connections.